Hi Kaas,
I have just installed an mp3 player in the 500 .
From the wires from the radio if u dont want all the hussle about connecting all of them to get full funcionality such as automatic dimming, power antenna etc, just wire your live of the radio to a Live from the car when ignition switch is on, and also the 'memory' wire from the radio to an always ON power source from the car. Multimeter comes in very handy to check the wires coming from the car. Dont forget your ground. And also your speakers...they should be paired so u won;'t miss them.
Usually only live and ground is enough to get it working butsome modern radios will not work unless you have both the memory and live (plus ground) wires connected. !!!!!!
Give me your mail address and i can mail u a diagram !!!:devil:
George